Make a Mind-Controlled Arduino Robot

96 Pages·2011·45.71 MB·English

Make a
Mind-
Controlled
Arduino
Robot
Tero Karvinen and Kimmo
Karvinen
Beijing • Cambridge • Farnham • Köln • Sebastopol • Tokyo
Make a Mind-Controlled Arduino Robot
by Tero Karvinen and Kimmo Karvinen
Copyright © 2012 Tero Karvinen, Kimmo Karvinen. All rights reserved.
Printed in the United States of America.
Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472.
O’Reilly books may be purchased for educational, business, or sales promotional use. Online
editions are also available for most titles (http://my.safaribooksonline.com). For more
information, contact our corporate/institutional sales department: [phone] or
[e-mail].
Editor: Brian Jepson
Production Editor: Teresa Elsey
Technical Editor: Ville Valtokari
Cover Designer: Mark Paglietti
Interior Designers: Ron Bilodeau and Edie Freedman
Illustrators: Tero Karvinen and Kimmo Karvinen
December 2011: First Edition.
Revision History for the First Edition:
December 13, 2011 First release
See http://oreilly.com/catalog/errata.csp?isbn=9781449311544 for release details.
Nutshell Handbook, the Nutshell Handbook logo, and the O’Reilly logo are registered trademarks
of O’Reilly Media, Inc. Make a Mind-Controlled Arduino Robot and related trade dress are trade-
marks of O’Reilly Media, Inc.
Many of the designations used by manufacturers and sellers to distinguish their products are
claimed as trademarks. Where those designations appear in this book, and O’Reilly Media, Inc.,
was aware of a trademark claim, the designations have been printed in caps or initial caps.
Important Message to Our Readers: The technologies discussed in this publication, the limi-
tations on these technologies that technology and content owners seek to impose, and the laws
actually limiting the use of these technologies are constantly changing. Thus, some of the projects
described in this publication may not work, may cause unintended harm to systems on which
they are used, or may not be consistent with current laws or applicable user agreements.
Your safety is your own responsibility, including proper use of equipment and safety gear, and
determining whether you have adequate skill and experience. Electricity and other resources
used for these projects are dangerous unless used properly and with adequate precautions, in-
cluding safety gear. These projects are not intended for use by children. While every precaution
has been taken in the preparation of this book, O’Reilly Media, Inc., and the authors assume no
responsibility for errors or omissions. Use of the instructions and suggestions in Make a Mind-
Controlled Arduino Robot is at your own risk. O’Reilly Media, Inc., and the authors disclaim all
responsibility for any resulting damage, injury, or expense. It is your responsibility to make sure
that your activities comply with applicable laws, including copyright.
ISBN: 978-1-449-31154-4
[LSI]
1323797765
Contents
Preface ............................................................... v
1/Building the Chassis ................................................. 1
Tools and Parts......................................................2
Parts............................................................2
Tools............................................................4
Servo Motors........................................................5
Attaching Servos..................................................5
Chassis.............................................................6
Making Holes.....................................................8
Painting the Chassis..................................................9
Attaching Servos to the Chassis.......................................12
Attaching the Line-Detecting Sensor...................................12
Wheels............................................................ 14
Attaching the RGB LED to Chassis.....................................15
Attaching the Power Switch to the Chassis..............................17
Attaching Arduino...................................................17
Battery Holder......................................................18
Attaching Solderless Breadboard......................................19
ScrewShield Holds Wires in Place.....................................20
2/Coding ............................................................ 21
Moving............................................................ 21
Connect Servos..................................................22
Hello Servo......................................................25
Calibrate Stopping Point..........................................26
Full Speed Forward...............................................26
Other Ways to Control Servos......................................27
Line Avoidance.....................................................28
Connect the Reflection Sensor.....................................28
Hello Reflection..................................................30
Don’t Cross the Black Line.........................................31
Battery, No Strings Attached.........................................33
Choosing Rechargeable Batteries..................................33
Connecting the Battery and Power Key............................. 34
Bells and Whistles...................................................38
Contents iii
Red, Green, and Blue LED.........................................38
Beeping Piezo................................................... 41
Setting Threshold with a Potentiometer.............................44
Everything But Your Mind............................................47
Code Structure..................................................47
Measuring Your Brains with MindWave.................................51
Hack MindWave Dongle...........................................51
Level Conversion with Resistors....................................53
Hello Attention!..................................................55
NeuroSky Protocol...............................................62
Complete Mind-Controlled Robot..................................... 63
Appendix: Building the ScrewShield ................................... 73
iv Contents
Preface
Shortly, you will build your own mind-controlled robot. But that’s just the
beginning of what you’ll be able to do. As you follow the explanations for
components and codes, you will thoroughly understand how your robot
works. You can keep applying the knowledge to your own robots and EEG-
based prototypes.
You’ll learn to
• Connect an inexpensive EEG device to Arduino
• Build a robot platform on wheels
• Calculate a percentage value from a potentiometer reading
• Mix colors with an RGB LED
• Play tones with a piezo speaker
• Write a program to avoid lines (tracks)
• Create simple movement routines
From Helsinki to San Francisco
In spring 2011, O’Reilly invited us to Maker Faire, which is the biggest DIY
festival in the world. We had to come up with a gimmick for the festival. It
had to be both new and simple enough so that everyone could understand
how it worked. Cheap EEG devices had just arrived to market and we thought
that it would be interesting to couple one of those with a robot.
As a result, we demonstrated the first prototype of the mind-controlled robot
at Maker Faire. It was a hit. People queued to try controlling the bot after
seeing it in action, as you can see in Figure P-1.
The bot is easy to use. You put on a headband and when you concentrate,
the bot moves. Focus more and it goes faster. And it’s a real robot too; it
avoids edges so that it stays on the table.
We built the first prototype (Figure P-2) with Ville Valtokari. The robot part
was based on soccer bot from Make: Arduino Bots and Gadgets (O’Reilly,
2011). We read the EEG with a NeuroSky MindWave. The early model had to
use a computer as a gateway between Arduino and MindWave, because we
Figure P-1. Attendees enjoying our robot at Maker Faire 2011, San Francisco
Bay area.
Figure P-2. First prototype of the Mind Controlled Robot.
were running the MindWave software and our own Python program on the
computer.
Maker Faire was great. Arduino was clearly the platform of choice for hard-
ware hackers. There were Arduino robots that could dive and others that
could fly. So did we stand a chance of getting any attention to our little bot?
vi Preface
Reactions
“It’s a fake!” Our favorite reaction was disbelief, as it showed that EEG tricks
were still new. As if what we were doing was so amazing that it simply had to
be just a magic trick. We only heard this about five times, though.
Most of the users simply thought the project was cool. Some were a little
skeptical at first, but trying is believing. About 300 visitors tried the device
and many more were watching (see Figure P-3 and Figure P-4).
Figure P-3. Robot at Maker Faire 2011, San Francisco Bay area.
We were surprised that it could work in a setting like that. Our prototype
could handle hundreds of visitors. Also, the NeuroSky EEG headband was
easy to put on and didn’t need any user training.
A couple of visitors had probably played with EEG before. They just noted
“Yep, it’s a NeuroSky” and started talking about something else. Luckily,
Brian Jepson had made a 3D-printed version of the soccer bot, so we had a
backup gadget to amuse them.
EEG in Your Living Room
Control a computer with just your mind. On one hand, it sounds almost like
a sci-fi fantasy. On the other, EEG (electroencephalography) was first used
in the early 20th century. What kept you waiting for the future?
EEG is the recording of electrical activity of the brain from the scalp, pro-
duced by neurons firing in the brain. The brain cortex produces tiny electrical
Preface vii
Figure P-4. Attendees control our robot at Maker Faire.
voltages (1–100 µV on the scalp). EEG doesn’t read your thoughts, but it can
tell your general state. For example, EEG can show if you are paying attention
or meditating.
The tiny voltages are easily masked by electrical noise from muscles and
ambient sources. EEG currents are measured in microvolts (µV), which are
millionths of a volt:
1 µV = 0.001 mV = 10-6 V
Noise from muscle and eye movement can be quite powerful compared to
this. In normal buildings, the electrical main’s current radiates a 50Hz or
60Hz electromagnetic field. In a laboratory setting, EEG is usually measured
in a room that has less interference. At home, the EEG unit must filter out
the troublesome signals.
viii Preface